CAMPS: computer-automated metacarpophalangeal profile system

The metacarpophalangeal profile (MCP) pattern has been proven useful in describing individuals with genetic and nongenetic syndromes. However, the measurement of the 19 bone lengths is a tedious procedure requiring use of hand vernier calipers, detailed normative data to be looked up in extensive tables, hand calculator, and manual graphing techniques. Presently there are no reports of microcomputer-automated systems for the accurate measurement, recording, analysis, and graphing of MCP profiles. We describe a computer-automated metacarpophalangeal profile system (CAMPS) that will assist in the derivation of the MCP profile. This program allows the user to select different program routines that perform the functions necessary for MCP profile construction. The "data acquisition module" (DAM) assists in bone length measurement from contact prints of hand radiographs and stores the 19 measurements on a floppy disk. The "standardization analysis module" (SAM) then compares the 19 measurements to age- and sex-matched normal data and converts the raw data to z-score values. The "Pearson product-moment correlation module" (PPM) generates a correlation coefficient describing the degree of similarity between the two hands measured and graphically illustrates the resulting scatterplot. The "MCP plotting module" (MCPM) provides a graphic plot of the 19 bones in either transverse rows or phalangeal rays on a dot-matrix printer or X-Y plotter.     

An examination of the electromyographic fatigue threshold test

Summary The purpose of this investigation was to examine times to exhaustion at various percentages of the electromyographic fatigue threshold (EMG_FT). Eight adult males [mean (SD), 21 (1) years] volunteered for the investigation. EMG_FT was derived by determining the rate of rise in the electrical activity of the vastus lateralis [using integrated electromyography (iEMG)] over time (iEMG slope) for four fatiguing power outputs during cycle ergometry. The four power outputs were then plotted as a function of the four iEMG slope coefficients. The y-intercept of the power output versus iEMG slope coefficient graph was defined as the EMG_FT. The intraclass correlation for repeated EMG_FT tests was R=0.65 (SEE=7 W) and there was no significant (P>0.05) difference between the mean (SD) values for test [260 (11) W] versus retest [262 (32) W]. Actual times to exhaustion were determined for work bouts at power outputs equal to 85, 100, 115, 130, and 145% of EMG_FT. The mean (SD) times to exhaustion for these work bouts were 495 (231), 225 (72), 135 (35), 94 (17), and 72 (14) s, respectively. A power curve was derived using the mean power outputs and mean times to exhaustion from the five rides at various percentages of EMG_FT. The power curve provided estimates of the power outputs which could be maintained for 30 and 60 min. There were significant (P<0.05) differences between the mean EMG_FT (260 W) and the power outputs which could be maintained for 30 (151 W) and 60 (125 W) min. EMG_FT overpredicted the estimated power outputs that could be maintained for 30 and 60 min by 42% and 52%, respectively.     

An EMG frequency-based test for estimating the neuromuscular fatigue threshold during cycle ergometry

The purposes of this investigation were twofold: (1) to determine if the model used for estimating the physical working capacity at the fatigue threshold (PWC_FT) from electromyographic (EMG) amplitude data could be applied to the frequency domain of the signal to derive a new fatigue threshold for cycle ergometry called the mean power frequency fatigue threshold (MPF_FT), and (2) to compare the power outputs associated with the PWC_FT, MPF_FT, ventilatory threshold (VT), and respiratory compensation point (RCP). Sixteen men [mean (SD) age = 23.4 (3.2) years] performed incremental cycle ergometer rides to exhaustion with bipolar surface EMG signals recorded from the vastus lateralis. There were significant (p < 0.05) mean differences for PWC_FT [mean (SD) = 168 (36) W] versus MPF_FT [208 (37) W] and VT [152 (33) W] versus RCP [205 (84) W], but no mean differences for PWC_FT versus VT or MPF_FT versus RCP. The mean difference between PWC_FT and MPF_FT may be due to the effects of specific metabolites that independently influence the time and frequency domains of the EMG signal. These findings indicated that the PWC_FT model could be applied to the frequency domain of the EMG signal to estimate MPF_FT. Furthermore, the current findings suggested that the PWC_FT may demarcate the moderate from heavy exercise domains, while the MPF_FT demarcates heavy from severe exercise intensities.     

Current perception threshold: an adjunctive test for detection of acquired demyelinating polyneuropathies

Current Perception Threshold (CPT) evaluation quantifies the sensory threshold to transcutaneous electrical stimulation of three sensory fiber subtypes: A-beta (2,000 Hz), A-delta (250 Hz) and C fibers (5 Hz). Demyelinating polyneuropathies tend to affect larger myelinated fibers before smaller unmyelinated fibers, and they usually begin at the proximal nerve roots or terminal axons, due to relative weakness of the blood-nerve barrier in these locations. Axonal polyneuropathies tend to affect smaller fibers before larger fibers, in a distal to proximal gradient. Ten patients with demyelinating polyneuropathy and ten patients with axonal polyneuropathy underwent CPT testing. CPT comparisons were made with regard to side-to-side asymmetries, fiber type involvement, and the ratio of fiber types involved. The C2, lateral antebrachial cutaneous, and sural distributions were examined bilaterally. Demyelinating polyneuropathies were detected with 50% sensitivity and 100% specificity. This diagnostic sensitivity is similar to that of published criteria based upon motor nerve conduction. CPT testing can distinguish demyelinating from axonal polyneuropathies. It may be particularly helpful in patients with predominantly sensory symptoms in whom EMG/NCS data may be equivocal, or in patients who decline EMG/NCS studies.     

A goodness-of-fit test for the polygenic threshold model: Application to pyloric stenosis

A new test of goodness of fit for the polygenic threshold model is proposed. This test, when applied to disorders showing different incidence rates in males and females, is designed to account for ascertainment in more detail than previously done by other investigators. This is accomplished by computing the expected distribution of nuclear families with more than one affected sib conditioned on several family-dependent variables, including whether each family was ascertained via only affeted boys or via at least one affected girl. A direct measure of the probability of observing a data set is thereby derived. The test, when applied to data on pyloric stenosis, exposes the critical nature of the ascertainment procedures. Different levels of statistical significance are obtained when mode of ascertainment is taken into account than when the mode of ascertainment is ignored.     

A goodness-of-fit test for the polygenic threshold model: Application to multiple sclerosis

Recently it has been suggested that multiple sclerosis may be a multifactorial disorder. We found in British Columbia 364 families (sibship size ? 2) in which at least one sibling was diagnosed as having “clinically definite” multiple sclerosis. The data were tested for goodness-of-fit to the multifactorial model using an analysis that considers various parameters including ascertainment probability, heritability, and sex-dependent prevalence rates. The results suggest that multiple sclerosis does not fit the multifactorial model. As an alternative genetic model we propose that a major gene could be responsible for at least a portion of the cases of multiple sclerosis.     

ROC analysis of dexamethasone suppression test threshold in suicide prediction after attempted suicide

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis function is associated with suicidal behavior. In suicide attempters with mood disorder, the non-suppressor status in the dexamethasone suppression test (DST) is associated with suicide indicating that HPA-axis hyperactivity is a biological risk factor for suicide and may be a useful predictor. The threshold of 5 microg/dl for cortisol levels measured at 08:00 a.m. or 4:00 p.m. following dexamethasone at 11:00 p.m. to define the DTS nonsuppression was derived as being optimal for the separation of melancholia and nonmelancholic conditions rather than the prediction of suicide. A different threshold may offer a better identification of suicide. The aim of this study was to find the optimal threshold level of post DST plasma cortisol at 4 p.m. for suicide prediction using receiver operating characteristics (ROC) analysis. A cohort of 106 depressed inpatients with an index suicide attempt admitted to the department of Psychiatry at the Karolinska University Hospital between 1980 and 2000, were submitted to DST and followed up for causes of death. During the follow-up (mean 17 years), 25 suicides (24%) were identified. The ROC analysis revealed that a lower threshold of 3.3 microg/dl for the nonsuppressor status predicted 17 of 25 suicides (sensitivity of 68%) compared with 15 of 25 suicides (sensitivity 60%) with a conventional threshold of 5 microg/dl at 4:00 p.m. In male suicide attempters the lower threshold for pathological DST result (3.3 microg/dl) changed the Odds ratio from 6.7 till 18. In female suicide attempters a higher threshold (7.3 microg/dl) optimised the value of DST as a biological test for suicide prediction indicating a gender difference.     

结合功能预测值与Variable Threshold检验法研究非同义SNP

背景：目前,随着全基因组关联分析的开展,成千上万的SNP基因型测序已经使遗传流行病学的研究进入一个新的阶段。通常,识别疾病相关的遗传位点依赖于DNA序列的单个碱基改变,而其中的一些改变可能影响蛋白质的结构和功能。因此出现在编码区域并导致氨基酸替代或插入的非同义SNP由于改变了氨基酸序列,更倾向于影响与复杂疾病易感性相关的蛋白质功能。 目的：结合非同义SNP的功能预测分数和Variable Threshold (VT)检验提高复杂疾病易感基因识别的准确率。 方法：文中首先对非同义SNP,计算它们的SIFT分数值和Polyphen-2分数值。然后筛选了35个疾病基因,对这些基因采用加权的VT检验进行分析,并与传统的关联分析进行了比较。 结果与结论：结果显示结合了SNP功能预测分数的VT检验,检验效能要高于传统的关联分析,提高了风险基因识别的准确率。     

A computer-automated,multi-center,multi-blinded,randomized control trial evaluating hypothesized spirit presence and communication

The gold standard in biomedical research is the multi-center, multi-blinded, randomized control trial (RCT). In pharmacological research the RCT is termed a Phase III clinical trial. This paper presents the core goals and RCT methods developed to investigate automated spirit presence and communication. The goals are: (1) to use currently available, reliable, and affordable technology (total hardware cost per system less than $4,000; these systems will be provided free to collaborating laboratories), (2) to automate data collection and real-time analyses employing specially designed software, (3) to only require a quiet space (used at night) in collaborating laboratories, (4) to not necessitate human subjects committee approvals at collaborating institutions (because the participants are hypothesized spirit participants), and (5) to enable international collaboration regardless of the investigator's personal beliefs about the hypothesis. The research design and methods meet a phrase popularized by Carl Sagan: “Extraordinary claims require extraordinary evidence.” The design minimizes false positives and false negatives. University affiliated investigators in established laboratories who regularly publish in peer reviewed journals, and are interested in collaborating in this RCT, are invited to contact the author.     

Electromyographic fatigue threshold of erector spinae muscle induced by a muscular endurance test in health men

PURPOSE: To identify the electromyographic fatigue threshold in the erector spinae muscle. METHODS: Eight 19 to 24-year-old male volunteers participated in this study, in which surface electrodes were used, as well as a biological signals acquisition module (Lynx) with a sampling frequency of 1000 Hz, a 1000 times gain, a 20 Hz high pass filter and a 500 Hz low pass filter. The test consisted of repeated isometric contractions of the erector spinae muscle in a 45 degrees hip flexion posture, with 30%, 40%, 50% and 60% of the maximum voluntary isometric contraction. RESULTS: A positive correlation of the RMS (root mean square) value as a function of time was found for most of the subjects with 40% (N = 6), 50% (N = 7) and 60% (N = 8) loads of the maximum voluntary isometric contraction. CONCLUSIONS: It was concluded, from this study, that the proposed protocol provides evidence, through the electromyographic signal, of the development of fatigue in the erector spinae muscle with loads of 40%, 50% and 60% of the maximum voluntary isometric contraction. The protocol also allows the electromyographic fatigue threshold and its probable applicability in the diagnosis of this phenomenon during repetitive activities to be determined.     

Anaerobic threshold

The general interest in the application of exercise testing to evaluate the work capacity or change in the functional ability of individuals has resulted in the development of a variety of non-invasive tests and test parameters such as the anaerobic threshold. This paper presents a computer program written in BASIC that determines the anaerobic threshold from expired respiratory gases collected from an incremental exercise test. Results are summarized in tabular as well as graphical format. The use of the incremental exercise test in conjunction with this computer program provide another means of efficiently determining the exercise capability of the patient.     

Evidence of an affinity threshold for IgE‐allergen binding in the percutaneous skin test reaction

BACKGROUND: Atopy is an aberrant immune response involving allergen-specific IgE production, though serum IgE concentration is not an entirely reliable diagnostic tool, particularly for epidemiological and genetic studies. There is no clear correlation between IgE and other indicators of atopy such as skin prick tests (SPT)s, and physiological associations are difficult to justify in cases with detectable IgE but negative SPT results. OBJECTIVE: IgE reflects the number of molecules available to produce an atopic response, but the degree of the response is determined by the binding strength (affinity) between receptor-bound IgE and the allergen. We sought to determine if there was an association between binding affinity and SPT results in people with histories of atopy. METHODS: Standard SPTs (whole allergen extracts) were administered to people with histories of sensitivities to ragweed and house dust mite. The concentrations and affinities of serum allergen-specific IgEs were determined using the purified allergens Amb a 1 and Der p 1. RESULTS: There was a positive correlation between weal area and allergen-specific IgE among SPT-positive donors. However, for those individuals with detectable amounts of allergen-specific IgE, there was considerable overlap of IgE values between SPT-positive and -negative groups. Among sensitized donors, IgE-allergen interactions were characterized by two or three specific reactions of very high affinity (K(A) range 10(8) -10(11) M). Negative SPT reactions were associated with lowered IgE binding affinities to major allergens. This delimited two groups with atopic disorders: specific IgE(+)/ SPT(+) and specific IgE(+)/SPT(-). CONCLUSION: The product of antibody affinity and concentration, which we define as antibody capacity (CAP = K(A) x IgE), is more informative with regard to describing allergen sensitivity than antibody concentration alone. Antibody binding capacity provides physiological evidence of atopy in some subjects who do not test positively by common methods and suggests an affinity threshold to produce a positive SPT reaction.     

When is a diagnostic test result positive? Decision tree models based on net utility and threshold

The question "When is a diagnostic test result positive?" can be addressed by clinical decision analysis. We developed two simple decision tree models for selecting appropriate cutoff levels: a net utility model and a threshold model. These models have been incorporated in a software program for desktop computers. We believe it is important for investigators to provide raw data on test performance, for three reasons. First, these data can be used in simple decision tree models to identify "appropriate" cutoff levels. Second, they can be used to evaluate empiric cutoff levels or decision rules. Third, they can be used to evaluate optimal cutoff levels for detailed decision trees depicting specific clinical problems.